Desulfurizing petroleum distillate fuels with clay in the first stage and liquid sulfur dioxide in the second stage



Dec. 14, 1954 5 c, HANEY ETAL 2,697,063

DESULFURIZING PETROLEUM DISTILLATE FUELS WITH CLAY IN THE FIRST STAGE AND LIQUID SULFUR v DIOXIDE IN THE SECOND STAGE Filed April 24, 1952 2 Sheets-Sheet 1 E: E 2 X Ill 1 1 5 O. 0. E (h LL LO It 0 p- O U m 1 r0 1 M 5 1 I' 3.

d I.|J 4 U I S INVENTORS STANLEY c. HANEY N JAMES D.MOORE ATTORNjXS Dec. 14, 1954 s c. HANEY ETAL 2,697,063

DESULFURIZING PETROLEUM DISTILLATE FUELS WITH CLAY IN THE FIRST STAGE AND LIQUID SULFUR DIOXIDE IN THE SECOND STAGE Filed April 24, l952 2 Sheets-Sheet 2 eoof- OLMSTED CLAY 4 150- 9 II I L BAUXITE oh. p I I J 700- ornzsn D nomom 0- CLAY 4 m U E. 2 U y- 550- X A z. X

usso FLORIDIN CLAY 600 I I I r 1000 2000 3000 4000 CATALYST AGE, BARR'ELS PER TON INVENTORS STANLEY c. HANEY JAMES D. MOORE BY ATTORN EYS DESULFURIZING PETROLEUM DISTILLATE FUELS WITH CLAY IN THE FIRST STAGE AND LIQUID SULFUR DIOXIDE IN THE SECOND STAGE Stanley C. Haney, Homewood, 111., and James D. Moore, Salt Lake City, Utah, assignors to Sinclair Refining Company, New York, N. Y., a corporation of Maine Application April 24, 1952, Serial No. 284,168

. Z Claims. 01. 196-48) Our invention relates to the desulfurization of petroleum distillates boiling in the diesel fuel range. Competitive demands are subjecting diesel fuels to lncreasmgly rigid requirements, particularly with respect to content of objectionable sulfur compounds, usually in the form of aromatic and aliphatic sulfur compounds, principally mercaptans, and total sulfur content. For example, the large increase in the use of high speed diesel engines, particularly by railroads, has led to theadoption by many railroads of a test for diesel fuels which is known as the St. Louis and South Western Railroad500 F. Copper Strip Corrosion test. The test is sensitive to both elementary and disulfide sulfur and thus a fuel which passes a standard corrosion test at 212 R, which is sensitive to only elementary sulfur, may fail the 500 F. corrosion test because of the presence of disulfides. A fuel failing the 500 F. corrosion test may cause nozzle clogging in diesel engines.- Thus to satisfactorily pass this test, mercaptan sulfur must be removed instead of merely converted to disulfides. However, the removal of objectionable aliphatic sulfur compounds does not appreciably lower the total sulfur content as aromatic sulfur compounds'remain. Therefore, to meet satisfactorily competitiverequirements the fuel must be treated to remove'aromatic as well as aliphatic sulfur compounds. Aromatic sulfur compounds may be removed by treating the fuel with sulfuric acid but because of the high consumption of acid, high treating losses and sludge disposal problems,it is not commercially attractive.

We have found that treating a petroleum distillate boiling in the diesel fuel range by a combination twostage process of contacting the distillate in the vapor phase at a temperature of about 600 to 700 F. with an-adsorptive clay type catalyst, e. g., Floridin clay, a commercially available. natural Florida fullers earth, and treating the distillate inthe liquid phase with liquid sulfur dioxide under extraction conditions elfectively'removes objectionable sulfur compounds and reduces total sulfur content to a level that satisfactorily meets competitive requirements. Moreover, we have found that unexpectedly high Floridin clay catalyst life is obtained in our combination process, e. g., over twice the life of other clay or bauxite catalysts in terms of barrels of fuel effectively-treated per ton of catalyst used. We have further found that the Floridin clay contacting step can be carried'out at substantially lower-temperatures, e. g. about 100 F. to 150 F. lower, to produce an oil of a desirable mercaptan sulfur content than are required when other clays or bauxite are used. In addition to the advantage of substantial heat savings, this lower contacting temperature is particularly advantageous as there is less danger of cracking of the fuel which would result in decreased yields and a less desirable fuel. The resulting diesel fuel is substantially mercaptan and disulfide free, satisfactorily passes the 500 F. copper strip corrosion test, is of low total sulfur content and of improved color and cetane index.

According to a preferred method of operation of our invention, we contact in the vapor phase a petroleum distillate boiling in the diesel fuel range, e. g., about 350 to 650 F., with Floridin clay at a temperature of about 600 to 700 F. and at moderate pressures, e. g., about atmospheric to 50 pounds per square inch. The clay treated distillate is then cooled and treated in the liquid phase with liquid sulfur dioxide under extraction conditions. An oil rafiinate is recovered and is a substantially mercaptan-free, low sulfur content,.e. g., about 0.2

lubricating oil.

Patented Dec. 14, 1954 per cent, non-corrosive diesel fuel and is obtained in high yields, e. g., about 90 to 95 per cent. We have found that this particular sequence of treating results in substantial heat savings particularly in treating a hot distillate, such as a distillate obtained directly from a refining tower, as this heat content is utilized in the clay contacting step whereas the heat content would be lost if the distillate were first treated with sulfur dioxide under low temperature extraction conditions followed by reheating for the clay contacting step.

The process of our invention effectively removes objectionable mercaptan sulfur from and reduces total sulfur content of petroleum distillates boiling in the diesel fuel range to produce high yields of superior diesel fuels while effecting substantial cost savings in terms of catalyst life, catalyst cost and heat requirements.

The adsorptive clay type catalyst useful in the process of our invention is Floridin clay which is a commercially available natural Florida fullers earth composed chiefly of the minerals attapulgite and montmorillonite, with a dominant attapulgite content. We have found that fresh Floridin and spent Floridin are equally effective and display the same surprisingly superior catalyst life. By spent Floridin, we mean Floridin that has been used in a refining process such as the adsorptive decolorizing of Therefore, in addition to the cost savings due to increased catalyst life a cost saving is realized in the use of spent Floridin clay.

The petroleum distillates that are effectively treated by the process of our invention are distillates boiling in the diesel fuel range, e. g., about 350 to 650 F., and may contain relatively high amounts of sulfur.

The preferred method of operation of our invention is illustrated in Figure 1 which is a schematic flow diagram of a two-stage process of Floridin clay contacting followed by sulfur dioxide extraction.

In the drawing, a petroleum distillate boiling in the diesel fuel range is introduced by line 1 to heater 2 where it is heated to about 600 to 700 F. The heated oil is passed by line 3 to reactor 4 where it is contacted in the vapor phase with a fixed bed of Floridin clay. The distillate is contacted with the clay at a rate of about 8 to 12 barrels of liquid oil per ton of clay per hour. Moderate pressures are used, e. g., from about atmospheric to 50 pounds per square inch. Operating conditions are selected so that substantially no cracking of constituents other than the sulfur compounds results. The clay-treated distillate is withdrawn by line 5 and passed to steam stripper 6 where it is treated with steam to remove hydrogen sulfide and light ends which are removed by line 7. The stripped clay-treated distillate is then passed by line 810 cooler 9 and by line 10 to extraction tower 11. In the extraction tower 11, the oil is contacted with liquid sulfur dioxide introduced by line 12 under extraction conditions. The extraction is carried out at temperatures in the range of about to 20 F. and at solvent to oil ratios of about 0.5 to 2 volumes of sulfur dioxide per volume of oil. An extract containing aromatic compounds is removed byline 13. An oil raffinate is removed by line 14, neutralized with caustic solution and the resulting oil is a substantially mercaptan-free, low sulfur-content, noncorrosive diesel fuel and is obtained in high yields, e. g., about to per cent.

While the above treating sequence is preferred for large scale commercial operation as substantial heat mercaptan sulfur level in the treated product and the using fresh or used Floridin clay catalysts, only .near the end of the contacting step was it necessary to raise the temperature above 650 F. to maintain a desirable mercaptan sulfur level. However, Olmsted clay required 4 with sulfur dioxide to removearomatic sulfur compounds.

The data were:

a temperature of 750 F. at 1000 barrels per ton cata- 5 Floridin so Treat lyst life and it was necessary to raise the temperature Treated (3315mm) to 800 F. shortly after. The bauxite catalyst was not much better, requiring a temperature of 750 F. at 1500 barrels per ton catalyst life. This clearly indicates the opelP-fiolli uniqueness of Floridin clay catalysts. gg gffg gfi fi The process of our inventlon will be further illus- In Yield, v01, Percent 91,6

spection: trated by the following examples 26 gl lg 8 cc"; a 8% 0 2? 08 ll 11!, ereen. Exafnp 500r. Cu. Strip Corr OK OK A sour West Texas heating 011 having a boiling range 15 Color, NPA 1 of 350 to 645 F. and an API gravity of 36.4 was treated 1n separate tests with Olmsted clay, bauxite, used Floridm clay and fresh Floridin clay. The results show that by combining Floridin clay The results were: contacting with sulfur dioxide treating a product is ob- Feed Products Catalyst Olmsted Bauxite Used Fresh Clay, Floridin Floridin 16-30 Clay, Clay, mesh 16-30 16-30 mesh mesh Operation:

Feed Rate B./T./Hr 10. 7 11.25 10. 96 Temp., "F 700-750 600-700 600-700 Catalyst Life, B./ 1, 842 2,102 4,553 4,496 Oil Recovered, Wt. Percent 99.19 98. 6 97. 6 99. 3 Inspection;

l\lercaptan Sulfur, Mg./100 cc 01.2 6.8 4.98 2.0 as Total Sulfur, Wt. Percent 0.78 0.58 0.57 0.61 0.61 500 F. Cu. Strip Corrosion Test... Fail OK OK OK Fall The results show that mercaptan sulfur was reduced tained that is mercaptan-free, of low total sulfur confrom 61.2 in the sour feed stock to 2 to 2.8 milligrams tent and of improved color. per 100 cc. in the treated distillate by the use of used We claim: or fresh Floridin clay while Olmsted clay and bauxite 40 1. A two-stage processfor desulfurizing petroleum disshow a reduction to only 6.8 and 4.98 mg./ 100 cc. tillate fuels which comprises contacting a petroleum disrespectively. The total sulfur content reduction was at tillate boiling in the diesel fuel range in the vapor phase least equal to the mercaptan sulfur removed. In add t on with the Floridin clay at a temperature of about 600 to this more effective mercaptan removal, the Florrdin to 700 F. and treating the distillate in the liquid phase clays produced an average of 4524 barrels of 011 per ton with liquid sulfur dioxide under extraction conditions and of catalyst while the Olmsted clay and bauxite produced only 1842 and 2162 barrels per ton respectively, an average of 2.25 times as great as the conventional catalysts clearly indicating the superior effectiveness of the Floridin clays.

clay.

The product obtained by the use of used Floridin clay passed the 500 F. Copper Strip Corrosion test. While the product obtained by the use of fresh Floridin clay did not pass the test, the failure is not considered serious since in commercial operations the mercaptan content could be controlled, by employing proper temperature, and kept to a low enough level so that even though disulfides were eventually formed their concentration would not be harmful.

Example 11 The product of treating the sour West Texas heating oil of Example I with used Floridin clay was treated Moreover, fresh Floridin clay produced a slightly higher yield than bauxite or Olmsted recovering a substantially mercaptan-free, low sulfurcontent diesel fuel.

2. A two-stage process for desulfurizing petroleum distillate fuels which comprises contacting apetroleum distillate boiling in the diesel fuel range in the vapor phase with Floridin clay at a temperature of about 600 to 700 F., withdrawinga clay-treated distillate, treating the clay-treated distillate in a second stage in the liquid phase with liquid sulfur dioxide under extraction conditions and recovering a substantially mercaptan-free, low sulfurcontent diesel fuel.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,273,224 Schulz Feb. 7, 1942 2,378,064 Conn June 12, 1945 2,507,861 Manley May 16, 1950 2,560,330 Brandon July 10, 1951 

1. A TWO-STAGE PROCESS FOR DESULFURIZING PETROLEUM DISTILLATE FUELS WHICH COMPRISES CONTACTING A PETROLEUM DISTILLATE BOILING IN THE DIESEL FUEL RANGE IN THE VAPOR PHASE WITH THE "FLORIDIN" CLAY AT A TEMPERATURE OF ABOUT 600* TO 700* F. AND TREATING THE DISTILLATE IN THE LIQUID PHASE WITH LIQUID SULFUR DIOXIDE UNDER EXTRACTION CONDITIONS AND RECOVERING A SUBSTANTIALLY MERCAPTAN-FREE, LOW SULFURCONTENT DIESEL FUEL. 